The invention relates generally to drive systems for skid steer vehicles. More particularly, it relates to skid steer vehicles having a direct gear drive.
Skid steer vehicles such as skid steer loaders were invented perhaps thirty years ago to provide a small vehicle on a highly maneuverable platform for working in close quarters on construction sites. They were called xe2x80x9cskid steer loadersxe2x80x9d since they had fixed axles, two per side, and could drive the wheels on one side of a vehicle at one speed and the wheels on the other side of the vehicle at a second speed. To turn the vehicles, the wheels on each side of the vehicle are driven at different speed, and even in opposite directions. It is this latter mode of operation that permits the vehicles to rotate about a vertical axis.
The drive mechanisms for these vehicles rely upon the fact that, on each side of the vehicle, the wheels were driven at the same speed. Each wheel is supported by an axle and the axles on the same side of the vehicle are driven by a single motor. The axles on the other side of the vehicle are driven by a second motor.
As these vehicles have developed, the axles were quite long and extended from the outside of the vehicle through a sidewall of the vehicle and into the interior of the vehicle, where they are joined via chains to a common hydraulic motor. Since chains are subject to wear, however, they need frequent replacement at some expense. Since they are located within the sidewalls of the vehicle, the chain tank takes up space that could be better used as space for the operator. The use of chains requires a longitudinally extending chain tank or chain bucket in which oil baths the chain. Since this tank extends from forward axle to rearward axle, it extends substantially the entire length of the vehicle.
By extending all the axles into the center of the vehicle and driving them from a common central chain tank, the drive mechanism consumes considerable interior space. Furthermore, by using chains to connect the motors to the axles, the vehicles require regular chain replacement, which increases down time. What is needed, therefore, is a skid steer vehicle with a drive system that does not require a chain tank or periodic replacement of a drive chain. What is also needed is a skid steer vehicle in which the drive components have been moved to the sides of the vehicle, thereby permitting a larger internal open space. It is an object of this invention to provide such a system in one or more claimed embodiments.
In accordance with a first embodiment of the invention, a skid steer vehicle is provided that has a direct drive system eliminating the extended drive chain of the traditional skid steer vehicle and replacing it with a gear and shaft drive that couples a hydraulic motor to a forward and aft drive wheel. This arrangement is provided on both sides of the vehicle. It disposes the drive elements adjacent to the sidewalls of the vehicle thereby reducing the intrusion of drive components near the center of the vehicle.
This system includes a hydraulic motor adjacent to a sidewall of the vehicle that is mounted to a gearbox including least one set of reduction gears. This gearbox splits the output to power two drive shafts, one extending forward and one extending aft to engage two axle housings. The forward and rear axle housing each contain two sets of reduction gears to further reduce speed and increase torque.
The vehicle has two such drive systems, one disposed on either side of the vehicle that each drive two wheels arranged in a fore-and-aft orientation. Each wheel is fixed to an axle extending from and supported by a corresponding one of the axle housings.